Could be as Stumpowitz says, if the lower tranmission seal has failed and oiled down the snubber area.

But the more likely cause is just a worn out plastic snubber ring, very common in these with what they are using for a snubber ring now, I've seen these wear out in less then 2years on machines with real high usuage.

Take the front off as directed and if you see no oil but do see all kinds of white powdery shavings around the bottom of the base in the snubber are, (under the milkstool), then you have a bad snubber.